LA302 Lost Bucket Roll Back Function

[TheOldHokie]

it’s already been ruled out…. Swapping the lines and the problem didn’t move with it means both spools have been tested in both directions and have been found working.
if one of the spools didn’t work, the problem would have moved to the other action. It didn’t. So the problem is beyond it, I.e, the hoses or connections on the hose half, or the cylinder.
Your hose to bucket test would rule out the connectors. If those work, what’s left is the cylinder.

He moved the male couplers snd nothing changed. I dont think we learned anything of value.

If we verify hydraulic flow through the bucket couplers we learn a lot.

Dan

 

[Henro]

it’s already been ruled out…. Swapping the lines and the problem didn’t move with it means both spools have been tested in both directions and have been found working.
if one of the spools didn’t work, the problem would have moved to the other action. It didn’t. So the problem is beyond it, I.e, the hoses or connections on the hose half, or the cylinder.
Your hose to bucket test would rule out the connectors. If those work, what’s left is the cylinder.

There are two cylinders...not just a cylinder. Based on the OP referencing that he had all four cylinders rebuilt in the past.

So what would happen if one would take the hoses off one of the cylinders, and connect them together. Seems like that would cause the same effect as what the OP is experiencing.

Seems at this point the issue is either the cylinders or the connectors at the valve. I know this is what jasonized is saying. I think so anyway.

If logic took me to this point, I would remove the hoses from one of the cylinders and cap them and see what happened. Then I would do it again with the other cylinder, after putting the hose back on the first cylinder. That way I would expect I could identify a failed cylinder that was letting oil flow through it, without the piston moving the rod.

Simplistic thinking by a guy with an electrical background I guess...LOL but true...

 

[TheOldHokie]

There are two cylinders...not just a cylinder. Based on the OP referencing that he had all four cylinders rebuilt in the past.

So what would happen if one would take the hoses off one of the cylinders, and connect them together. Seems like that would cause the same effect as what the OP is experiencing.

Seems at this point the issue is either the cylinders or the connectors at the valve. I know this is what jasonized is saying. I think so anyway.

If logic took me to this point, I would remove the hoses from one of the cylinders and cap them and see what happened. Then I would do it again with the other cylinder, after putting the hose back on the first cylinder. That way I would expect I could identify a failed cylinder that was letting oil flow through it, without the piston moving the rod.

Simplistic thinking by a guy with an electrical background I guess...LOL but true...

If you remove just the return hose at the male coupler you get all of that and more in one simple test:

If you get flow and no movement one or both of the cylinders is bad.

If you get no flow the supply sde coupler or spool is bad

If you get flow and the bucket curls the return side coupler is bad OR the return to tank is obstructed.

Armed with that information we can narrow the search.

Dan

 

[Jasonized]

He moved the male couplers snd nothing changed. I dont think we learned anything of value.

If we verify hydraulic flow through the bucket couplers we learn a lot.

Dan

Hmm… he swapped functions, not just single hoses. He said he swapped the pairs. So if the problem did not move, and the other function worked, then yes, those connections are working on that end.

if the female side on one function did not work, then the problem would stay on that side, and the problem would look like it moved. It didn’t. So it can’t be that side of the hoses, or the spools. Well, it *could* be intermittent, but that’s on the other end of statistical likeliness, I.e., low probability.

So, hoses or cylinder. Could be clogged hose? Naaa… but then again, your hose flow tests would eliminate that!
I advocated swapping hoses as the quickest, least messy test to split the problem from the valve side from the loader side. Besides, he already did that before posting here, so it eliminated the spool and connector bodies on the spool.. moving along!

 

[Trimley]

TLDR:

First thoughts, check hoses.
Still nothing.

Check linkeage at the stick actuator/valve would be me.

 

[Jasonized]

TLDR:

First thoughts, check hoses.
Still nothing.

Check linkeage at the stick actuator would be me.

But we know the actuator works, because when he swapped hoses, the side that was on the curl would then be on lift, and that still worked. So the lift side worked when connected to lift, and the curl side worked when connected to lift. So, it must be working on that side!

 

[Trimley]

But we know the actuator works, because when he swapped hoses, the side that was on the curl would then be on lift, and that still worked. So the lift side worked when connected to lift, and the curl side worked when connected to lift. So, it must be working on that side!

But is the curl connection at the joystick connected?

 

[Jasonized]

But is the curl connection at the joystick connected?

Let's try a graphic...

Okay, so looking at this, the black is the tractor side of the system. Valves, joystick, female connectors, the works.
The red is the lift parts; hoses, cylinders.
The blue is the curl parts; hoses, cylinders.
Since OP told us that when he swapped the hoses, the lift still worked and the curl didn't, then everything in black must be working. Also everything in Red. The only places the problem could be are now located in the blue section. Either the hoses or the cylinders.

Old Hokey said to disconnect the hose from the cylinder side, and then run the joystick to see if fluid comes out of the hose. If you do this for both hoses, then you have eliminated the hoses as the problems. This leaves cylinder. Since they are a simple T fitting from one cylinder to another, a failed cylinder that is shorted (i.e., oil just passes through without resistance) could cause it to fail in this manner.
Okay?

 

[TheOldHokie]

Let's try a graphic...

View attachment 114781
Okay, so looking at this, the black is the tractor side of the system. Valves, joystick, female connectors, the works.
The red is the lift parts; hoses, cylinders.
The blue is the curl parts; hoses, cylinders.
Since OP told us that when he swapped the hoses, the lift still worked and the curl didn't, then everything in black must be working. Also everything in Red. The only places the problem could be are now located in the blue section. Either the hoses or the cylinders.

Old Hokey said to disconnect the hose from the cylinder side, and then run the joystick to see if fluid comes out of the hose. If you do this for both hoses, then you have eliminated the hoses as the problems. This leaves cylinder. Since they are a simple T fitting from one cylinder to another, a failed cylinder that is shorted (i.e., oil just passes through without resistance) could cause it to fail in this manner.
Okay?

Disconnect ONE hose and you test both quick connectors and the cylinders. Why is this so hard to understand?

Dsn

 

[Jasonized]

Disconnect ONE hose and you test both quick connectors and the cylinders. Why is this so hard to understand?

Dsn

Simple. Fast, easy to do without tools, no mess. Gives you almost everything your test does, except the final hose length.

As a first diagnostic test, it has a higher info to effort ratio.

 

[TheOldHokie]

Simple. Fast, easy to do without tools, no mess. Gives you almost everything your test does, except the final hose length.

As a first diagnostic test, it has a higher info to effort ratio.

OK - I have provided my input.
Now you help the man fix his loader.

Dan

 

[Trimley]

Let's try a graphic...

View attachment 114781
Okay, so looking at this, the black is the tractor side of the system. Valves, joystick, female connectors, the works.
The red is the lift parts; hoses, cylinders.
The blue is the curl parts; hoses, cylinders.
Since OP told us that when he swapped the hoses, the lift still worked and the curl didn't, then everything in black must be working. Also everything in Red. The only places the problem could be are now located in the blue section. Either the hoses or the cylinders.

Old Hokey said to disconnect the hose from the cylinder side, and then run the joystick to see if fluid comes out of the hose. If you do this for both hoses, then you have eliminated the hoses as the problems. This leaves cylinder. Since they are a simple T fitting from one cylinder to another, a failed cylinder that is shorted (i.e., oil just passes through without resistance) could cause it to fail in this manner.
Okay?

Copy that. That eliminates the valve. Given tests, the (a) cylinder may have a stopage.

 

[Jasonized]

OK - I have provided my input.
Now you help the man fix his loader.

Dan

We have both been helping. Not to mention others have also been helping from this site.

I just fail to understand why you have to be so combative with everyone if they suggest something that isn’t exactly the same approach you suggested.

Looking at the document posted by someone else about testing a double acting cylinder, just removing one hose and seeing if fluid comes out doesn’t completely diagnose if the cylinder is bypassing or not, depending on it’s position. While I have a healthy suspicion that the test isn’t the only way to test something, I’m not going to jump on someone and beat them up if they suggest it.

When I am working on something, I’m willing to try a simple 30 second test that gives information without a mess. It provides information, which I might not have had before, so it was a good use of my time. Besides, the OP had already done it!

Will I move on to testing the lines? Yes. Will I then look at testing the cylinders? Yup! But first, I would isolate one cylinder from the other, so I can be sure I’m testing only one of the pair, since one bypassing cylinder would cause the problem. So disconnecting a hose and putting a plug on it to isolate and test the other cylinder would be my next step. swap plug and repeat, if I didn’t win the 50/50 lottery and tested a functional cylinder.
I’d be really careful though, as one cylinder attempting to curl and the other not will cause twisting stress on the frame, and of course, will possibly squeeze fluid out of the disconnected cylinder. Maybe I would disconnect the cylinder from one side of the frame, just to be safe. Don’t know. I’m not doing it yet!

 

[TheOldHokie]

We have both been helping. Not to mention others have also been helping from this site.

I just fail to understand why you have to be so combative with everyone if they suggest something that isn’t exactly the same approach you suggested.

Looking at the document posted by someone else about testing a double acting cylinder, just removing one hose and seeing if fluid comes out doesn’t completely diagnose if the cylinder is bypassing or not, depending on it’s position. While I have a healthy suspicion that the test isn’t the only way to test something, I’m not going to jump on someone and beat them up if they suggest it.

When I am working on something, I’m willing to try a simple 30 second test that gives information without a mess. It provides information, which I might not have had before, so it was a good use of my time. Besides, the OP had already done it!

Will I move on to testing the lines? Yes. Will I then look at testing the cylinders? Yup! But first, I would isolate one cylinder from the other, so I can be sure I’m testing only one of the pair, since one bypassing cylinder would cause the problem. So disconnecting a hose and putting a plug on it to isolate and test the other cylinder would be my next step. swap plug and repeat, if I didn’t win the 50/50 lottery and tested a functional cylinder.
I’d be really careful though, as one cylinder attempting to curl and the other not will cause twisting stress on the frame, and of course, will possibly squeeze fluid out of the disconnected cylinder. Maybe I would disconnect the cylinder from one side of the frame, just to be safe. Don’t know. I’m not doing it yet!

I was trying to keep this simple and definitive. Not combative just frustrated by the level of confusion being introduced.

If you disconnect that return side hose and observe oil flow you have DIRECT evidence of what's happening in the circuit:

If you get flow and cylinder movement you KNOW pressure is being supplied and the cylinder is operating correctly..

If you get flow but no cylinder movement you KNOW that one or both of the cylinders is bypassing

That's directly observed and definitive results.

Dan

 

[Henro]

I was trying to keep this simple and definitive. Not combative just frustrated by the level of confusion being introduced.

If you disconnect that return side hose and observe oil flow you have DIRECT evidence of what's happening in the circuit:

If you get flow and cylinder movement you KNOW pressure is being supplied and the cylinder is operating correctly..

If you get flow but no cylinder movement you KNOW that one or both of the cylinders is bypassing

That's directly observed and definitive results.

Dan

Dan, I think I get what you are saying. Seems return hose did not register initially. You mean the hose that would bring fluid back to the control valve I assume. Rather than the hose that returns fluid to the hydraulic tank.

So the quick disconnect would be separated and the hose would be removed from the disconnect for this test. I get it. Very simple and the easiest thing to try. One logical step at a time, as they say...

 

[TheOldHokie]

Dan, I think I get what you are saying. Seems return hose did not register initially. You mean the hose that would bring fluid back to the control valve I assume. Rather than the hose that returns fluid to the hydraulic tank.

So the quick disconnect would be separated and the hose would be removed from the disconnect for this test. I get it. Very simple and the easiest thing to try. One logical step at a time, as they say...

You got it and yes terminology gets very confusing.

Power the supply side portion of the cylinder work circuit with the "return side" open to atmosphere and you get durect observable confirmation of flow and cylinder movement.

Dan

 

[Rusty46]

Stop swapping things around. You are just adding to the confusion and risk getting things misconnected. You have lost one function - curl. Stick to just that circuit. You told is this was a spontaneous failure while operating so I am ruling out misconnections. Let's test borh halves of the curl circuit.

With tractor off and all couplers connected as normal:

1. Disconnect the hose from the male coupler going to the rod end of the bucket cylinders, start tractor and try to curl. You should get oil out of the disconnected coupler. If no.oil flow that coupler is defective or the spool is not shifting. Stop here.

2. If you get oil in test #1 reconnect hose and disconnect the hose on the male coupler going to base end of bucket cylinder, start tractor and try curl. You should get oil from that hose and bucket should curl.

Reconnect all hoses and report findings.

Dan

Dan - 1. I disconnected the hoses to both bucket cylinder rod ends. There was some initial drainage. I started the tractor and tried the curl (roll back). Hydraulic fluid flowed out of both disconnected hoses. I reconnected both hoses to cylinders.

2. I disconnected the hoses to both bucket cylinder base ends. There was some initial drainage. I started the tractor and tried the curl. No hydraulic fluid flowed out of either disconnected hose. Hydraulic fluid did flow out of the open connection of the right side (looking forward from operator's seat) cylinder. The bucket did NOT curl.

Bad cylinder?

 

[GreensvilleJay]

If you had one bad cylinder , I'd expect the other to try to move, maybe slowly....
To diagnose,
1) I'd disconnect and blow out ALL of the hoses from valve to cylinders using low pressure air.
2) I'd get 2 'plugs' and disconnect one cylinder,use plugs to ,well, plug those 2 lines
3) test to see what happens

IF the connected cylinder does function, the disconnected one is bad.
If it doesn't, put plugs where the 2nd cylinder connects, reconnect 1st cylinder and test.

 

[TheOldHokie]

Dan - 1. I disconnected the hoses to both bucket cylinder rod ends. There was some initial drainage. I started the tractor and tried the curl (roll back). Hydraulic fluid flowed out of both disconnected hoses. I reconnected both hoses to cylinders.

2. I disconnected the hoses to both bucket cylinder base ends. There was some initial drainage. I started the tractor and tried the curl. No hydraulic fluid flowed out of either disconnected hose. Hydraulic fluid did flow out of the open connection of the right side (looking forward from operator's seat) cylinder. The bucket did NOT curl.

Bad cylinder?

Let's start over. Please do just this one test.

Go to the valve where the male disconnects on the hoses are plugged into the female disconnects on the valve. Identify which one of the hoses goes to the base end of the rod cylinders.

Disconnect JUST THAT ONE hose from the male quick connect.

Put the hose in a clean bucket, start the tractor and briefly move joystick to curl. Shut it down and reconnect tje hose

Now answer BOTH of these two questions and I will answer yours.

1. Did you get a flow of oil out of the hose?
2. Did the cylinders/bucket move?

Dan

 

[TheOldHokie]

Dan - 1. I disconnected the hoses to both bucket cylinder rod ends. There was some initial drainage. I started the tractor and tried the curl (roll back). Hydraulic fluid flowed out of both disconnected hoses. I reconnected both hoses to cylinders.

2. I disconnected the hoses to both bucket cylinder base ends. There was some initial drainage. I started the tractor and tried the curl. No hydraulic fluid flowed out of either disconnected hose. Hydraulic fluid did flow out of the open connection of the right side (looking forward from operator's seat) cylinder. The bucket did NOT curl.

Bad cylinder?

I went back and reread this post. I did not pay ebough sttention when I saw you were disconnecting hoses at the cylinders. My apologies- your second test is basically what I wanted. If you got flow out of the base end of the right cylinder and the cylinder did not move the cylinder is bypassing.

Dan